Transcricothyroid, intraoperative monitoring of the vagus nerve.

Objective: To develop a reliable, user-friendly, intraoperative, electromyographic monitoring technique to decrease the incidence of injury to the recurrent and superior laryngeal nerves.

Design: Prospective, nonrandomized, clinical trial of a nerve monitoring technique.

Setting: Private tertiary care community hospital.

Patients: A population-based sample of 31 patients scheduled to undergo thyroid surgery was enrolled consecutively. Included in the study were patients older than 18 years who were scheduled for surgery and who were able to provide informed consent. Exclusion criteria were pregnancy, implanted metallic devices, and history of laryngeal surgery, injury, paresis, hoarseness, or paralysis. No patients were excluded, and all completed the study and returned for follow-up visits.

Interventions: Twenty-nine patients required total thyroidectomy, of which 10 involved malignancy, and the other 2 patients required lobectomy. Each patient completed the Voice Handicap Index and underwent a preoperative fiberoptic laryngeal examination. Continuous monitoring was performed using a widely available, commercial nerve integrity monitor and a paired electrode placed into the cricothyroid space under direct vision. Postoperatively, participants completed a follow-up Voice Handicap Index survey and underwent a laryngeal examination.

Main Outcome Measures: The incidence of vocal paresis, or paralysis, and the preoperative and postoperative voice handicap score were recorded. The usefulness of the device based on the surgeon's subjective and immediate postoperative impressions was rated on a visual analog scale.

Results: Sixty-two recurrent laryngeal nerves were identified with continuous electromyographic monitoring. Vocal cord paresis or paralysis was not observed. Postoperative Voice Handicap Index scores were unchanged from preoperative assessment. The technique was given a rating of 1 (most useful) on a 5-point scale in 70% of cases.

Conclusions: The technique described is sensitive, easy to use, accurate, and associated with a high degree of surgeon satisfaction. This technique is not associated with additional risk to the patient and offers the potential to reduce injury. Monitoring provides assurance that the nerve is intact and functioning prior to extubation.